[TRAFODION-2723] Add check to NATable cache for snapshot info

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 2.2.0
• Fix Version/s: 2.2.0
• Component/s: sql-cmp
• Environment: any, using snapshot scans
• Assignee: Hans Zeller
• Reporter: Hans Zeller
• Created: 21/Aug/17 22:25
• Updated: 21/Aug/17 23:10
• Resolved: 21/Aug/17 23:10

Description

TRAFODION-2716 added code to read snapshot info conditionally. This means that most NATable cache entries will not have this information. Now, if a user turns on snapshot scan after accessing some tables, the cache entries will prevent snapshot scans from happening, or they may create unnecessary snapshots.

Like it is done for other CQDs that influence NATable cache entries, we need to invalidate the cache if the TRAF_TABLE_SNAPSHOT_SCAN has gone from NONE to some value other than NONE. There is no need to check in the other direction, extra snapshot scan info won't hurt.